/*
 * utils.c - various utility functions used in pppd.
 *
 * Copyright (c) 1999-2002 Paul Mackerras. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 *
 * 2. The name(s) of the authors of this software must not be used to
 *    endorse or promote products derived from this software without
 *    prior written permission.
 *
 * 3. Redistributions of any form whatsoever must retain the following
 *    acknowledgment:
 *    "This product includes software developed by Paul Mackerras
 *     <paulus@samba.org>".
 *
 * THE AUTHORS OF THIS SOFTWARE DISCLAIM ALL WARRANTIES WITH REGARD TO
 * THIS SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
 * AND FITNESS, IN NO EVENT SHALL THE AUTHORS BE LIABLE FOR ANY
 * SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN
 * AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING
 * OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 */

#include "netif/ppp/ppp_opts.h"
#if PPP_SUPPORT /* don't build if not configured for use in lwipopts.h */

#if 0 /* UNUSED */
#include <stdio.h>
#include <ctype.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <signal.h>
#include <errno.h>
#include <fcntl.h>
#include <syslog.h>
#include <netdb.h>
#include <time.h>
#include <utmp.h>
#include <pwd.h>
#include <sys/param.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <sys/time.h>
#include <sys/resource.h>
#include <sys/stat.h>
#include <sys/socket.h>
#include <netinet/in.h>
#ifdef SVR4
#include <sys/mkdev.h>
#endif
#endif /* UNUSED */

#include <ctype.h>  /* isdigit() */

#include "netif/ppp/ppp_impl.h"

#include "netif/ppp/fsm.h"
#include "netif/ppp/lcp.h"

#if defined(SUNOS4)
extern char *strerror();
#endif

static void ppp_logit(int level, const char *fmt, va_list args);
static void ppp_log_write(int level, char *buf);
#if PRINTPKT_SUPPORT
static void ppp_vslp_printer(void *arg, const char *fmt, ...);
static void ppp_format_packet(const u_char *p, int len,
                              void (*printer) (void *, const char *, ...), void *arg);

struct buffer_info
{
    char *ptr;
    int len;
};
#endif /* PRINTPKT_SUPPORT */

/*
 * ppp_strlcpy - like strcpy/strncpy, doesn't overflow destination buffer,
 * always leaves destination null-terminated (for len > 0).
 */
size_t ppp_strlcpy(char *dest, const char *src, size_t len)
{
    size_t ret = strlen(src);

    if (len != 0)
    {
        if (ret < len)
            strcpy(dest, src);
        else
        {
            strncpy(dest, src, len - 1);
            dest[len - 1] = 0;
        }
    }
    return ret;
}

/*
 * ppp_strlcat - like strcat/strncat, doesn't overflow destination buffer,
 * always leaves destination null-terminated (for len > 0).
 */
size_t ppp_strlcat(char *dest, const char *src, size_t len)
{
    size_t dlen = strlen(dest);

    return dlen + ppp_strlcpy(dest + dlen, src, (len > dlen ? len - dlen : 0));
}


/*
 * ppp_slprintf - format a message into a buffer.  Like sprintf except we
 * also specify the length of the output buffer, and we handle
 * %m (error message), %v (visible string),
 * %q (quoted string), %t (current time) and %I (IP address) formats.
 * Doesn't do floating-point formats.
 * Returns the number of chars put into buf.
 */
int ppp_slprintf(char *buf, int buflen, const char *fmt, ...)
{
    va_list args;
    int n;

    va_start(args, fmt);
    n = ppp_vslprintf(buf, buflen, fmt, args);
    va_end(args);
    return n;
}

/*
 * ppp_vslprintf - like ppp_slprintf, takes a va_list instead of a list of args.
 */
#define OUTCHAR(c)	(buflen > 0? (--buflen, *buf++ = (c)): 0)

int ppp_vslprintf(char *buf, int buflen, const char *fmt, va_list args)
{
    int c, i, n;
    int width, prec, fillch;
    int base, len, neg, quoted;
    unsigned long val = 0;
    const char *f;
    char *str, *buf0;
    const unsigned char *p;
    char num[32];
#if 0 /* need port */
    time_t t;
#endif /* need port */
    u32_t ip;
    static char hexchars[] = "0123456789abcdef";
#if PRINTPKT_SUPPORT
    struct buffer_info bufinfo;
#endif /* PRINTPKT_SUPPORT */

    buf0 = buf;
    --buflen;
    while (buflen > 0)
    {
        for (f = fmt; *f != '%' && *f != 0; ++f)
            ;
        if (f > fmt)
        {
            len = f - fmt;
            if (len > buflen)
                len = buflen;
            memcpy(buf, fmt, len);
            buf += len;
            buflen -= len;
            fmt = f;
        }
        if (*fmt == 0)
            break;
        c = *++fmt;
        width = 0;
        prec = -1;
        fillch = ' ';
        if (c == '0')
        {
            fillch = '0';
            c = *++fmt;
        }
        if (c == '*')
        {
            width = va_arg(args, int);
            c = *++fmt;
        }
        else
        {
            while (isdigit(c))
            {
                width = width * 10 + c - '0';
                c = *++fmt;
            }
        }
        if (c == '.')
        {
            c = *++fmt;
            if (c == '*')
            {
                prec = va_arg(args, int);
                c = *++fmt;
            }
            else
            {
                prec = 0;
                while (isdigit(c))
                {
                    prec = prec * 10 + c - '0';
                    c = *++fmt;
                }
            }
        }
        str = 0;
        base = 0;
        neg = 0;
        ++fmt;
        switch (c)
        {
        case 'l':
            c = *fmt++;
            switch (c)
            {
            case 'd':
                val = va_arg(args, long);
                if ((long)val < 0)
                {
                    neg = 1;
                    val = (unsigned long) - (long)val;
                }
                base = 10;
                break;
            case 'u':
                val = va_arg(args, unsigned long);
                base = 10;
                break;
            default:
                OUTCHAR('%');
                OUTCHAR('l');
                --fmt;		/* so %lz outputs %lz etc. */
                continue;
            }
            break;
        case 'd':
            i = va_arg(args, int);
            if (i < 0)
            {
                neg = 1;
                val = -i;
            }
            else
                val = i;
            base = 10;
            break;
        case 'u':
            val = va_arg(args, unsigned int);
            base = 10;
            break;
        case 'o':
            val = va_arg(args, unsigned int);
            base = 8;
            break;
        case 'x':
        case 'X':
            val = va_arg(args, unsigned int);
            base = 16;
            break;
#if 0 /* unused (and wrong on LLP64 systems) */
        case 'p':
            val = (unsigned long) va_arg(args, void *);
            base = 16;
            neg = 2;
            break;
#endif /* unused (and wrong on LLP64 systems) */
        case 's':
            str = va_arg(args, char *);
            break;
        case 'c':
            num[0] = va_arg(args, int);
            num[1] = 0;
            str = num;
            break;
#if 0 /* do we always have strerror() in embedded ? */
        case 'm':
            str = strerror(errno);
            break;
#endif /* do we always have strerror() in embedded ? */
        case 'I':
            ip = va_arg(args, u32_t);
            ip = lwip_ntohl(ip);
            ppp_slprintf(num, sizeof(num), "%d.%d.%d.%d", (ip >> 24) & 0xff,
                         (ip >> 16) & 0xff, (ip >> 8) & 0xff, ip & 0xff);
            str = num;
            break;
#if 0 /* need port */
        case 't':
            time(&t);
            str = ctime(&t);
            str += 4;		/* chop off the day name */
            str[15] = 0;	/* chop off year and newline */
            break;
#endif /* need port */
        case 'v':		/* "visible" string */
        case 'q':		/* quoted string */
            quoted = c == 'q';
            p = va_arg(args, unsigned char *);
            if (p == NULL)
                p = (const unsigned char *)"<NULL>";
            if (fillch == '0' && prec >= 0)
            {
                n = prec;
            }
            else
            {
                n = strlen((const char *)p);
                if (prec >= 0 && n > prec)
                    n = prec;
            }
            while (n > 0 && buflen > 0)
            {
                c = *p++;
                --n;
                if (!quoted && c >= 0x80)
                {
                    OUTCHAR('M');
                    OUTCHAR('-');
                    c -= 0x80;
                }
                if (quoted && (c == '"' || c == '\\'))
                    OUTCHAR('\\');
                if (c < 0x20 || (0x7f <= c && c < 0xa0))
                {
                    if (quoted)
                    {
                        OUTCHAR('\\');
                        switch (c)
                        {
                        case '\t':
                            OUTCHAR('t');
                            break;
                        case '\n':
                            OUTCHAR('n');
                            break;
                        case '\b':
                            OUTCHAR('b');
                            break;
                        case '\f':
                            OUTCHAR('f');
                            break;
                        default:
                            OUTCHAR('x');
                            OUTCHAR(hexchars[c >> 4]);
                            OUTCHAR(hexchars[c & 0xf]);
                        }
                    }
                    else
                    {
                        if (c == '\t')
                            OUTCHAR(c);
                        else
                        {
                            OUTCHAR('^');
                            OUTCHAR(c ^ 0x40);
                        }
                    }
                }
                else
                    OUTCHAR(c);
            }
            continue;
#if PRINTPKT_SUPPORT
        case 'P':		/* print PPP packet */
            bufinfo.ptr = buf;
            bufinfo.len = buflen + 1;
            p = va_arg(args, unsigned char *);
            n = va_arg(args, int);
            ppp_format_packet(p, n, ppp_vslp_printer, &bufinfo);
            buf = bufinfo.ptr;
            buflen = bufinfo.len - 1;
            continue;
#endif /* PRINTPKT_SUPPORT */
        case 'B':
            p = va_arg(args, unsigned char *);
            for (n = prec; n > 0; --n)
            {
                c = *p++;
                if (fillch == ' ')
                    OUTCHAR(' ');
                OUTCHAR(hexchars[(c >> 4) & 0xf]);
                OUTCHAR(hexchars[c & 0xf]);
            }
            continue;
        default:
            *buf++ = '%';
            if (c != '%')
                --fmt;		/* so %z outputs %z etc. */
            --buflen;
            continue;
        }
        if (base != 0)
        {
            str = num + sizeof(num);
            *--str = 0;
            while (str > num + neg)
            {
                *--str = hexchars[val % base];
                val = val / base;
                if (--prec <= 0 && val == 0)
                    break;
            }
            switch (neg)
            {
            case 1:
                *--str = '-';
                break;
            case 2:
                *--str = 'x';
                *--str = '0';
                break;
            default:
                break;
            }
            len = num + sizeof(num) - 1 - str;
        }
        else
        {
            len = strlen(str);
            if (prec >= 0 && len > prec)
                len = prec;
        }
        if (width > 0)
        {
            if (width > buflen)
                width = buflen;
            if ((n = width - len) > 0)
            {
                buflen -= n;
                for (; n > 0; --n)
                    *buf++ = fillch;
            }
        }
        if (len > buflen)
            len = buflen;
        memcpy(buf, str, len);
        buf += len;
        buflen -= len;
    }
    *buf = 0;
    return buf - buf0;
}

#if PRINTPKT_SUPPORT
/*
 * vslp_printer - used in processing a %P format
 */
static void ppp_vslp_printer(void *arg, const char *fmt, ...)
{
    int n;
    va_list pvar;
    struct buffer_info *bi;

    va_start(pvar, fmt);
    bi = (struct buffer_info *) arg;
    n = ppp_vslprintf(bi->ptr, bi->len, fmt, pvar);
    va_end(pvar);

    bi->ptr += n;
    bi->len -= n;
}
#endif /* PRINTPKT_SUPPORT */

#if 0 /* UNUSED */
/*
 * log_packet - format a packet and log it.
 */

void
log_packet(p, len, prefix, level)
u_char *p;
int len;
char *prefix;
int level;
{
    init_pr_log(prefix, level);
    ppp_format_packet(p, len, pr_log, &level);
    end_pr_log();
}
#endif /* UNUSED */

#if PRINTPKT_SUPPORT
/*
 * ppp_format_packet - make a readable representation of a packet,
 * calling `printer(arg, format, ...)' to output it.
 */
static void ppp_format_packet(const u_char *p, int len,
                              void (*printer) (void *, const char *, ...), void *arg)
{
    int i, n;
    u_short proto;
    const struct protent *protp;

    if (len >= 2)
    {
        GETSHORT(proto, p);
        len -= 2;
        for (i = 0; (protp = protocols[i]) != NULL; ++i)
            if (proto == protp->protocol)
                break;
        if (protp != NULL)
        {
            printer(arg, "[%s", protp->name);
            n = (*protp->printpkt)(p, len, printer, arg);
            printer(arg, "]");
            p += n;
            len -= n;
        }
        else
        {
            for (i = 0; (protp = protocols[i]) != NULL; ++i)
                if (proto == (protp->protocol & ~0x8000))
                    break;
            if (protp != 0 && protp->data_name != 0)
            {
                printer(arg, "[%s data]", protp->data_name);
                if (len > 8)
                    printer(arg, "%.8B ...", p);
                else
                    printer(arg, "%.*B", len, p);
                len = 0;
            }
            else
                printer(arg, "[proto=0x%x]", proto);
        }
    }

    if (len > 32)
        printer(arg, "%.32B ...", p);
    else
        printer(arg, "%.*B", len, p);
}
#endif /* PRINTPKT_SUPPORT */

#if 0 /* UNUSED */
/*
 * init_pr_log, end_pr_log - initialize and finish use of pr_log.
 */

static char line[256];		/* line to be logged accumulated here */
static char *linep;		/* current pointer within line */
static int llevel;		/* level for logging */

void
init_pr_log(prefix, level)
const char *prefix;
int level;
{
    linep = line;
    if (prefix != NULL)
    {
        ppp_strlcpy(line, prefix, sizeof(line));
        linep = line + strlen(line);
    }
    llevel = level;
}

void
end_pr_log()
{
    if (linep != line)
    {
        *linep = 0;
        ppp_log_write(llevel, line);
    }
}

/*
 * pr_log - printer routine for outputting to log
 */
void
pr_log (void *arg, const char *fmt, ...)
{
    int l, n;
    va_list pvar;
    char *p, *eol;
    char buf[256];

    va_start(pvar, fmt);
    n = ppp_vslprintf(buf, sizeof(buf), fmt, pvar);
    va_end(pvar);

    p = buf;
    eol = strchr(buf, '\n');
    if (linep != line)
    {
        l = (eol == NULL) ? n : eol - buf;
        if (linep + l < line + sizeof(line))
        {
            if (l > 0)
            {
                memcpy(linep, buf, l);
                linep += l;
            }
            if (eol == NULL)
                return;
            p = eol + 1;
            eol = strchr(p, '\n');
        }
        *linep = 0;
        ppp_log_write(llevel, line);
        linep = line;
    }

    while (eol != NULL)
    {
        *eol = 0;
        ppp_log_write(llevel, p);
        p = eol + 1;
        eol = strchr(p, '\n');
    }

    /* assumes sizeof(buf) <= sizeof(line) */
    l = buf + n - p;
    if (l > 0)
    {
        memcpy(line, p, n);
        linep = line + l;
    }
}
#endif /* UNUSED */

/*
 * ppp_print_string - print a readable representation of a string using
 * printer.
 */
void ppp_print_string(const u_char *p, int len, void (*printer) (void *, const char *, ...), void *arg)
{
    int c;

    printer(arg, "\"");
    for (; len > 0; --len)
    {
        c = *p++;
        if (' ' <= c && c <= '~')
        {
            if (c == '\\' || c == '"')
                printer(arg, "\\");
            printer(arg, "%c", c);
        }
        else
        {
            switch (c)
            {
            case '\n':
                printer(arg, "\\n");
                break;
            case '\r':
                printer(arg, "\\r");
                break;
            case '\t':
                printer(arg, "\\t");
                break;
            default:
                printer(arg, "\\%.3o", (u8_t)c);
                /* no break */
            }
        }
    }
    printer(arg, "\"");
}

/*
 * ppp_logit - does the hard work for fatal et al.
 */
static void ppp_logit(int level, const char *fmt, va_list args)
{
    char buf[1024];

    ppp_vslprintf(buf, sizeof(buf), fmt, args);
    ppp_log_write(level, buf);
}

static void ppp_log_write(int level, char *buf)
{
    LWIP_UNUSED_ARG(level); /* necessary if PPPDEBUG is defined to an empty function */
    LWIP_UNUSED_ARG(buf);
    PPPDEBUG(level, ("%s\n", buf) );
#if 0
    if (log_to_fd >= 0 && (level != LOG_DEBUG || debug))
    {
        int n = strlen(buf);

        if (n > 0 && buf[n - 1] == '\n')
            --n;
        if (write(log_to_fd, buf, n) != n
                || write(log_to_fd, "\n", 1) != 1)
            log_to_fd = -1;
    }
#endif
}

/*
 * ppp_fatal - log an error message and die horribly.
 */
void ppp_fatal(const char *fmt, ...)
{
    va_list pvar;

    va_start(pvar, fmt);
    ppp_logit(LOG_ERR, fmt, pvar);
    va_end(pvar);

    LWIP_ASSERT("ppp_fatal", 0);   /* as promised */
}

/*
 * ppp_error - log an error message.
 */
void ppp_error(const char *fmt, ...)
{
    va_list pvar;

    va_start(pvar, fmt);
    ppp_logit(LOG_ERR, fmt, pvar);
    va_end(pvar);
#if 0 /* UNUSED */
    ++error_count;
#endif /* UNUSED */
}

/*
 * ppp_warn - log a warning message.
 */
void ppp_warn(const char *fmt, ...)
{
    va_list pvar;

    va_start(pvar, fmt);
    ppp_logit(LOG_WARNING, fmt, pvar);
    va_end(pvar);
}

/*
 * ppp_notice - log a notice-level message.
 */
void ppp_notice(const char *fmt, ...)
{
    va_list pvar;

    va_start(pvar, fmt);
    ppp_logit(LOG_NOTICE, fmt, pvar);
    va_end(pvar);
}

/*
 * ppp_info - log an informational message.
 */
void ppp_info(const char *fmt, ...)
{
    va_list pvar;

    va_start(pvar, fmt);
    ppp_logit(LOG_INFO, fmt, pvar);
    va_end(pvar);
}

/*
 * ppp_dbglog - log a debug message.
 */
void ppp_dbglog(const char *fmt, ...)
{
    va_list pvar;

    va_start(pvar, fmt);
    ppp_logit(LOG_DEBUG, fmt, pvar);
    va_end(pvar);
}

#if PRINTPKT_SUPPORT
/*
 * ppp_dump_packet - print out a packet in readable form if it is interesting.
 * Assumes len >= PPP_HDRLEN.
 */
void ppp_dump_packet(ppp_pcb *pcb, const char *tag, unsigned char *p, int len)
{
    int proto;

    /*
     * don't print data packets, i.e. IPv4, IPv6, VJ, and compressed packets.
     */
    proto = (p[0] << 8) + p[1];
    if (proto < 0xC000 && (proto & ~0x8000) == proto)
        return;

    /*
     * don't print valid LCP echo request/reply packets if the link is up.
     */
    if (proto == PPP_LCP && pcb->phase == PPP_PHASE_RUNNING && len >= 2 + HEADERLEN)
    {
        unsigned char *lcp = p + 2;
        int l = (lcp[2] << 8) + lcp[3];

        if ((lcp[0] == ECHOREQ || lcp[0] == ECHOREP)
                && l >= HEADERLEN && l <= len - 2)
            return;
    }

    ppp_dbglog("%s %P", tag, p, len);
}
#endif /* PRINTPKT_SUPPORT */

#if 0 /* Unused */

/*
 * complete_read - read a full `count' bytes from fd,
 * unless end-of-file or an error other than EINTR is encountered.
 */
ssize_t
complete_read(int fd, void *buf, size_t count)
{
    size_t done;
    ssize_t nb;
    char *ptr = buf;

    for (done = 0; done < count; )
    {
        nb = read(fd, ptr, count - done);
        if (nb < 0)
        {
            if (errno == EINTR)
                continue;
            return -1;
        }
        if (nb == 0)
            break;
        done += nb;
        ptr += nb;
    }
    return done;
}

/* Procedures for locking the serial device using a lock file. */
#ifndef LOCK_DIR
#ifdef __linux__
#define LOCK_DIR	"/var/lock"
#else
#ifdef SVR4
#define LOCK_DIR	"/var/spool/locks"
#else
#define LOCK_DIR	"/var/spool/lock"
#endif
#endif
#endif /* LOCK_DIR */

static char lock_file[MAXPATHLEN];

/*
 * lock - create a lock file for the named device
 */
int
lock(dev)
char *dev;
{
#ifdef LOCKLIB
    int result;

    result = mklock (dev, (void *) 0);
    if (result == 0)
    {
        ppp_strlcpy(lock_file, dev, sizeof(lock_file));
        return 0;
    }

    if (result > 0)
        ppp_notice("Device %s is locked by pid %d", dev, result);
    else
        ppp_error("Can't create lock file %s", lock_file);
    return -1;

#else /* LOCKLIB */

    char lock_buffer[12];
    int fd, pid, n;

#ifdef SVR4
    struct stat sbuf;

    if (stat(dev, &sbuf) < 0)
    {
        ppp_error("Can't get device number for %s: %m", dev);
        return -1;
    }
    if ((sbuf.st_mode & S_IFMT) != S_IFCHR)
    {
        ppp_error("Can't lock %s: not a character device", dev);
        return -1;
    }
    ppp_slprintf(lock_file, sizeof(lock_file), "%s/LK.%03d.%03d.%03d",
                 LOCK_DIR, major(sbuf.st_dev),
                 major(sbuf.st_rdev), minor(sbuf.st_rdev));
#else
    char *p;
    char lockdev[MAXPATHLEN];

    if ((p = strstr(dev, "dev/")) != NULL)
    {
        dev = p + 4;
        strncpy(lockdev, dev, MAXPATHLEN - 1);
        lockdev[MAXPATHLEN - 1] = 0;
        while ((p = strrchr(lockdev, '/')) != NULL)
        {
            *p = '_';
        }
        dev = lockdev;
    }
    else if ((p = strrchr(dev, '/')) != NULL)
        dev = p + 1;

    ppp_slprintf(lock_file, sizeof(lock_file), "%s/LCK..%s", LOCK_DIR, dev);
#endif

    while ((fd = open(lock_file, O_EXCL | O_CREAT | O_RDWR, 0644)) < 0)
    {
        if (errno != EEXIST)
        {
            ppp_error("Can't create lock file %s: %m", lock_file);
            break;
        }

        /* Read the lock file to find out who has the device locked. */
        fd = open(lock_file, O_RDONLY, 0);
        if (fd < 0)
        {
            if (errno == ENOENT) /* This is just a timing problem. */
                continue;
            ppp_error("Can't open existing lock file %s: %m", lock_file);
            break;
        }
#ifndef LOCK_BINARY
        n = read(fd, lock_buffer, 11);
#else
        n = read(fd, &pid, sizeof(pid));
#endif /* LOCK_BINARY */
        close(fd);
        fd = -1;
        if (n <= 0)
        {
            ppp_error("Can't read pid from lock file %s", lock_file);
            break;
        }

        /* See if the process still exists. */
#ifndef LOCK_BINARY
        lock_buffer[n] = 0;
        pid = atoi(lock_buffer);
#endif /* LOCK_BINARY */
        if (pid == getpid())
            return 1;		/* somebody else locked it for us */
        if (pid == 0
                || (kill(pid, 0) == -1 && errno == ESRCH))
        {
            if (unlink (lock_file) == 0)
            {
                ppp_notice("Removed stale lock on %s (pid %d)", dev, pid);
                continue;
            }
            ppp_warn("Couldn't remove stale lock on %s", dev);
        }
        else
            ppp_notice("Device %s is locked by pid %d", dev, pid);
        break;
    }

    if (fd < 0)
    {
        lock_file[0] = 0;
        return -1;
    }

    pid = getpid();
#ifndef LOCK_BINARY
    ppp_slprintf(lock_buffer, sizeof(lock_buffer), "%10d\n", pid);
    write (fd, lock_buffer, 11);
#else
    write(fd, &pid, sizeof (pid));
#endif
    close(fd);
    return 0;

#endif
}

/*
 * relock - called to update our lockfile when we are about to detach,
 * thus changing our pid (we fork, the child carries on, and the parent dies).
 * Note that this is called by the parent, with pid equal to the pid
 * of the child.  This avoids a potential race which would exist if
 * we had the child rewrite the lockfile (the parent might die first,
 * and another process could think the lock was stale if it checked
 * between when the parent died and the child rewrote the lockfile).
 */
int
relock(pid)
int pid;
{
#ifdef LOCKLIB
    /* XXX is there a way to do this? */
    return -1;
#else /* LOCKLIB */

    int fd;
    char lock_buffer[12];

    if (lock_file[0] == 0)
        return -1;
    fd = open(lock_file, O_WRONLY, 0);
    if (fd < 0)
    {
        ppp_error("Couldn't reopen lock file %s: %m", lock_file);
        lock_file[0] = 0;
        return -1;
    }

#ifndef LOCK_BINARY
    ppp_slprintf(lock_buffer, sizeof(lock_buffer), "%10d\n", pid);
    write (fd, lock_buffer, 11);
#else
    write(fd, &pid, sizeof(pid));
#endif /* LOCK_BINARY */
    close(fd);
    return 0;

#endif /* LOCKLIB */
}

/*
 * unlock - remove our lockfile
 */
void
unlock()
{
    if (lock_file[0])
    {
#ifdef LOCKLIB
        (void) rmlock(lock_file, (void *) 0);
#else
        unlink(lock_file);
#endif
        lock_file[0] = 0;
    }
}

#endif /* Unused */

#endif /* PPP_SUPPORT */
